Conventional examples of materials that are widely used for resin-made components that reflect light, such as components for automobile lamps and the like, include thermosetting resins such as unsaturated polyester resin and bulk molding compound (BMC), and aluminum-made materials. Although thermosetting resins are superior to aluminum-made materials in terms of being light-weight, there is demand for further weight reduction. Moreover, thermosetting resins also suffer from problems such as the complexity of an operation for vapor depositing aluminum on a shaped product and contamination of an operational environment with dust and the like.
Consequently, there is progress toward switching materials to thermoplastic resins such as polyetherimide and high-heat resistance polycarbonate for which the operation of aluminum vapor deposition is simple. However, these thermoplastic resins are not sufficiently light-weight and a material having even lower specific gravity would be desirable in consideration of environmental impact and energy efficiency.
Polyphenylene ether resins have properties such as excellent mechanical properties, electrical properties, acid resistance, alkali resistance, and heat resistance, low specific gravity and water absorbency, and good dimensional stability. Accordingly, polyphenylene ether resins are widely used as materials for home appliances, OA devices, office machines, information devices, automobiles, and so forth.
It is also anticipated that due, in particular, to their property of low specific gravity, polyphenylene ether resin compositions may be used in light-reflective shaped product applications. However, when a polyphenylene ether resin composition is used in such an application, there is demand for higher heat resistance and rigidity, better shaping fluidity, higher light reflection properties, and greater ease of aluminum vapor deposition. Moreover, a shaped product thereof is expected to have good surface external appearance, brightness, and so forth.
The addition of an inorganic filler such as glass fiber, carbon fiber, mica, or talc is commonly used as a method for improving the heat resistance and mechanical properties of a thermoplastic resin including polyphenylene ether resin. However, this method leads to significant loss of toughness of the resin and shaped product surface gloss even when only a small amount of inorganic filler is added, which makes it highly difficult to adopt a resin composition obtained by this method for light-reflective shaped product applications.
Moreover, compounding of rubber-reinforced polystyrene (high-impact polystyrene; HIPS) is widely adopted for imparting impact resistance on polyphenylene ether resins. However, compounding of rubber-reinforced polystyrene tends to lead to loss of brightness of the resultant shaped product in the same manner as when an inorganic filler is added.
A resin composition that is provided with an excellent balance of light weight, heat resistance, fluidity, and mechanical properties through a blend of a polyphenylene ether resin and a liquid-crystal polyester has been disclosed as a technique in relation to automobile lamp components formed from polyphenylene ether resin compositions (for example, refer to PTL 1).
Moreover, a technique has been disclosed in relation to a resin composition suitable for automobile lamp component applications and the like that has improved resin heat aging resistance and film shaped product external appearance as a consequence of a specific stabilizer being added to a resin composition containing a polyphenylene ether resin in a relatively high concentration (for example, refer to PTL 2).
Furthermore, a technique has been disclosed for improving a conventional polyphenylene ether resin in terms of heat stability, white spots (protrusions of 30 μm or more in diameter that are formed in a shaped product due to the presence of pigment aggregates in proximity to the surface of the shaped product), and so forth by modifying the polyphenylene ether resin with an acrylic acid ester, such as stearyl acrylate, or the like (for example, refer to PTL 3, 4, and 5).